One ultrasound is enough for some DVT patients

Thrombus
© Steve Gschmeissner
Photo Researchers, Inc.

A retrospective study suggests that 1 negative whole-leg compression ultrasound (CUS) may be sufficient to withhold anticoagulation therapy for some low-risk patients with a suspected lower extremity deep vein thrombosis (DVT).

While CUS is widely accepted as a reliable way to confirm and exclude deep vein thrombosis (DVT) in the proximal veins, its accuracy of indicating distal DVT has been in question.  Since 25% of distal clots can move into proximal veins, standard of care has included multiple CUS tests 5 to 7 days after the first.

Stacy A. Johnson, MD, at the University of Utah School of Medicine in Salt Lake City, and colleagues revisited 7 previous studies evaluating 4,731 patients in total. They  determined that the combined venous thromboembolism event rate at 3 months after 1 negative CUS was 0.57%, which is relatively low-risk.

The team used studies from MEDLINE, EMBASE, CINAHL, LILACS, Cochrane, and Health Technology Assessments databases. Studies that met specific criteria were included. Each must have evaluated patients with suspected lower limb DVT with a single whole-leg CUS, patients must have been monitored for at least 90 days in which they received no anticoagulation therapy, and objective confirmation of venous thromboembolism during the follow-up period.

Seven studies were included, 6 were prospective cohort studies and 1 was a randomized controlled trial.

Thirty-four of 4731 (0.7%) patients died from venous thromboembolism, 9 (26.5%) of which were not objectively confirmed as being caused by venous thromboembolism  and occurred in patients who were either acutely ill and hospitalized or had advanced cancer. Distal DVT was the cause of death in 11 (32.4%) patients, 7 (20.6%) had proximal DVT, and 7 (20.6) had nonfatal pulmonary embolism.

The researchers believe their results to be the first reported pooled risk assessment of venous thromboembolism following a single negative lower extremity whole-leg CUS result.

The authors concluded, “In summary, withholding anticoagulation following a single negative whole-leg CUS result was associated with a low risk for venous thromboembolism during a 3-month follow-up in patients with suspected DVT. Using a single negative whole-leg CUS result as the sole diagnostic modality in patients with high pretest probability of DVT requires further study.”
The article was published in the February 3 issue of JAMA.